In turbine blades and combustors exposed to high-temperature environments, cooling is performed in order to inhibit a reduction in service life due to thermal damage. As a cooling mechanism that performs such cooling, an impingement cooling mechanism is often employed in the case of, for example, low pressure loss of a turbine nozzle or the like being required in a turbine blade. In an impingement cooling mechanism in a turbine blade, a hollow impingement plate in which a plurality of impingement holes are formed is installed in the interior of the turbine blade. Blowing a cooling gas that is supplied to the interior of the impingement plate against the inner wall surface of the blade body via the impingement holes cools the blade main body.
In this kind of impingement cooling mechanism, between the impingement plate and the blade main body, cooling gas after being ejected from the impingement holes flows along the surface of the impingement plate and inner surface of blade main body. The flow of this cooling gas after ejection is generally called a crossflow (hereinbelow, the flow of the cooling gas after ejection shall be described as a crossflow). However, when a crossflow is formed between the impingement plate and the blade main body, the cooling gas that is ejected from the impingement holes positioned on the downstream side of this crossflow ends up being swept into (entrained into) the crossflow, and therefore hindered from reaching the blade main body. Therefore, the further downstream of the crossflow, the more the impingement cooling effect decreases.
Conventionally, a structure has been proposed that provides, on the upstream side of the impingement hole, a shielding plate (shielding means) that shields the crossflow (for example, refer to Patent Document 1, Patent Document 2).